Field
The present invention relates to a light emitting module, and more particularly, to a lens for surface illumination and a light emitting module for surface illumination including the same.
Discussion of the Background
A light emitting module for backlighting a liquid crystal display or a light emitting module for surface illumination used in a surface illumination apparatus may include light emitting elements mounted on a circuit board and a lens for diffusing light emitted from the light emitting elements at a wide angle. Light may be uniformly irradiated over a wide area with a smaller number of light emitting elements by uniformly diffusing the light emitted from the light emitting elements using the lens.
FIGS. 1A and 1B are schematic cross-sectional view and perspective view for describing a light emitting module and a lens according to the related art.
Referring to FIGS. 1A and 1B, the light emitting module includes a circuit board 100, a light emitting element 200, and a lens 300. The circuit board 100 may be a printed circuit board provided with a circuit for supplying power to the light emitting element 200.
The light emitting element 200 may include a light emitting diode chip 210, a molding part 230 covering the light emitting diode chip 210, and a package substrate 250. The molding part 230 includes a phosphor configured to convert a wavelength of light emitted from the light emitting diode chip 210, and which may have a lens shape. The package substrate 250 may have a recess for mounting the light emitting diode chip 210. The light emitting element 200 is electrically connected to the circuit board 100.
Meanwhile, the lens 300 may include a lower surface 310 and an upper surface 350, and may further include a flange 370 and leg parts 390. The leg parts 390 are attached on the circuit board 100 so that the lens 300 is disposed over the light emitting element 200. As illustrated in FIG. 1B, the leg parts 390 are may be configured as a group of three and disposed at regular triangular apexes.
The lens 300 includes a light incident surface 330 on which light is incident from the light emitting element 200 and a light emitting surface 350 from which the incident light is emitted. The light incident surface 330 is an inner surface of a concave part 320, which may be shell-shaped, which is disposed on the lower surface 310 of the lens 300. The concave part 320 is disposed on the light emitting element 200 and thus the light emitted from the light emitting element 200 is incident into the lens 300 through the light incident surface 330. The light emitting surface 350 emits the light incident into the lens 300 at a wide orientation angle.
The light emitting module according to the related art diffuses the light emitted from the light emitting element 200 through the lens 300 to implement uniform light over a wide area. However, the light emitting element 200 mounted on the circuit board 100 may adopt the package substrate 250, and therefore a size of the light emitting element 200 may be relatively large. Therefore, an inlet and a height of the concave part 320 for forming the light incident surface 330 of the lens 300 may be relatively large, and as a result, it may be difficult to slim the lens 300. In addition, the beam angle spread of light emitted from the light emitting element 200 may be relatively narrow, and therefore it may be difficult to diffuse light through the lens 300.
Further, the light emitting element 200 is disposed under the lower surface 310 of the lens 300 and therefore some of the light emitted from the light emitting element 200 may not be incident into the lens 300 and may be lost below the lower surface 310 of the lens 300.